Non-rigid point cloud registration for middle ear diagnostics with endoscopic optical coherence tomography.

PURPOSE: Middle ear infection is the most prevalent inflammatory disease, especially among the pediatric population. Current diagnostic methods are subjective and depend on visual cues from an otoscope, which is limited for otologists to identify pathology. To address this shortcoming, endoscopic optical coherence tomography (OCT) provides both morphological and functional in vivo measurements of the middle ear. However, due to the shadow of prior structures, interpretation of OCT images is challenging and time-consuming. To facilitate fast diagnosis and measurement, improvement in the readability of OCT data is achieved by merging morphological knowledge from ex vivo middle ear models with OCT volumetric data, so that OCT applications can be further promoted in daily clinical settings. METHODS: We propose C2P-Net: a two-staged non-rigid registration pipeline for complete to partial point clouds, which are sampled from ex vivo and in vivo OCT models, respectively. To overcome the lack of labeled training data, a fast and effective generation pipeline in Blender3D is designed to simulate middle ear shapes and extract in vivo noisy and partial point clouds. RESULTS: We evaluate the performance of C2P-Net through experiments on both synthetic and real OCT datasets. The results demonstrate that C2P-Net is generalized to unseen middle ear point clouds and capable of handling realistic noise and incompleteness in synthetic and real OCT data. CONCLUSIONS: In this work, we aim to enable diagnosis of middle ear structures with the assistance of OCT images. We propose C2P-Net: a two-staged non-rigid registration pipeline for point clouds to support the interpretation of in vivo noisy and partial OCT images for the first time. Code is available at: https://gitlab.com/nct_tso_public/c2p-net.

Endoscopic Optical Coherence Tomography for Evaluation of Success of Tympanoplasty.

OBJECTIVE: After tympanoplasty, it is often challenging to differentiate between different causes of a remaining air bone gap (ABG). Optical coherence tomography (OCT) offers a new approach for combined morphologic and functional measurements of the tympanic membrane and adjacent parts of the middle ear. Thus, it provides valuable diagnostic information in patients with a reduced sound transfer after middle ear surgery. PATIENT AND INTERVENTION: A patient with history of tympanoplasty and a persistent ABG was investigated with endoscopic OCT before revision surgery. MAIN OUTCOME MEASURES: The oscillation behavior and the thickness of the reconstructed tympanic membrane was determined. The oscillation amplitudes of the inserted prosthesis were compared to a finite element model simulation and to the clinical findings and the audiometric data of the patient. RESULTS: OCT measurements showed a reduced oscillation amplitude of the prosthesis while revealing an aerated middle ear and good coupling of the prosthesis. Transfer loss measured by OCT showed a similar progression as the ABG measured by pure-tone audiometry with a mean divergence of 4.45 dB. CONCLUSION: Endoscopic OCT is a promising tool for the evaluation of tympanoplasty outcome. It supports established otologic diagnostics and can help differentiating between different causes of conductional hearing loss.

Outcome parameters in speech audiometry: retrospective analysis of data and reporting quality in clinical studies.

OBJECTIVES: The use of standardized outcome parameters is essential for the comparability of clinical studies. Pure-tone audiometry and speech audiometry are widely used, but there is no systematic evaluation of the outcome parameters in clinical application. Nevertheless, there is presumably a great heterogeneity especially in the field of speech audiometry. This study presents a snapshot of the current situation of documentation and usage of outcome parameters in otologic research. STUDY DESIGN: Retrospective study of existing literature analyzing common speech audiometric test material and procedure MAIN OUTCOME MEASURES: Intervention Studies from 2012 to 2016 concerning hearing ability were eligible for evaluation. Studies were analyzed with regard to study design, pathology and intervention, speech audiometric parameters, pure-tone audiometry, implementation of reporting standards and journal related data. RESULTS: 279 studies were included. Over 50% of the analyzed studies lacked proper documentation. In the remaining studies, there was a broad variance concerning the documented speech audiometric parameters, most often with a fixed presentation level of 65 dB SPL. CONCLUSION: The lack of generally used standards for reporting hearing outcomes makes it difficult to compare results of different clinical studies. An adequate description of the methods would be a first and important step in improving reports on audiological outcomes.